Cognitive decline with pupil constriction independent of subjective fatigue during prolonged esports across player expertise levels*

Cognitive fatigue, a transient cognitive decline stemming from extended mental and physical activity, is well established in conventional contexts. However, its manifestation and self-awareness during digital pursuits, as an integrated style of mental and physical activity, notably in electronic sports (esports), remain underexplored. Here we show that, using virtual football as a representative model for esports, prolonged esports cause cognitive fatigue with pupil constriction, independent of subjective fatigue across player expertise. Casual and hardcore esports players engaged in an intensive 3 h gaming session, and sense of fatigue, executive function, pupil diameter as a potential signifier, and other physiological parameters were recorded. Subjective fatigue remained unchanged for up to 2 h, but increased after 3 h, inversely linked to reported enjoyment, in both groups of players. Executive function, assessed by flanker interference, decreased after 2 h and 3 h in casual players. The accuracy of the flanker task decreased after 2 h and 3 h in hardcore players, despite an initial accuracy edge. Pupil diameter decreased after 2 h and 3 h and correlated with cognitive performance decline but diverged from subjective fatigue in both player types. Our findings clearly suggest a disparity between actual cognitive decline and subjective fatigue awareness in esports, transcending levels of player expertise. Pupil constriction is a potential neurobiological marker integrating divergent cognitive and subjective fatigue during digital engagement.